Working with userDefinedData

The userDefinedData is mainly used in the frontend to allow users to pass in additional information during the time of verification. The data is passed into the customVerificationHook function on your SelfVerificationRoot contract, which can be used as desired to perform custom logic.

The userDefinedData passed in the QRCode gets converted from a string to bytes. You will have to convert it back from bytes to a string again and work on top of that.

One use case that userDefinedData can be used for is to define what disclosures the user is asked to provide. In the example below, the userDefinedData is used create a key that maps to a particular setup of the verification config.

Setting a config

When setting a config just creating the config is not enough. You should register the config with the hub and this method will also return the config id.

//internal map that stores from hash(data) -> configId
mapping(uint256 => uint256) public configs;

function setConfig(
    string memory configDesc, 
    SelfUtils.UnformattedVerificationConfigV2 config
) public {
    //create the key
    uint256 key = uint256(keccak256(bytes(configDesc)));
    //create the hub compliant config struct
    SelfStructs.VerificationConfigV2 verificationConfig = 
        SelfUtils.formatVerificationConfigV2(_verificationConfig);
    //register and get the id
    uint256 verificationConfigId = 
        IIdentityVerificationHubV2(identityVerificationHubV2Address)
        .setVerificationConfigV2(verificationConfig);
    //set it in the key
    configs[key] = verificationConfigId;
}

Change the getConfigId in the SelfVerificationRoot

Now we just have to change the getConfigId that returns the config ids from this map. This is pretty simple as now we just have to hash the existing bytes:

function getConfigId(
    bytes32 destinationChainId,
    bytes32 userIdentifier,
    bytes memory userDefinedData
) public view virtual returns (bytes32) {
    //the string is already converted to bytes
    uint256 key = keccak256(userDefinedData);
    return configs[key];
}